PTEN Loss and PD-L1 Expression of Different Histological Patterns of Prostate Cancer

Aims: Although several studies have evaluated PTEN loss in Prostatic Adenocarcinoma (PCa), PTEN loss correlation with different histological patterns only has a few studies. Although several studies have evaluated PD-L1 expression in PCa and its correlation with Gleason scores, as far as we know, there are no prior studies that have included a comparison between PD-L1 expression and histological patterns of PCa. This study aims to evaluate PTEN loss and PD-L1 expression by immunohistochemistry in different histological patterns of PCa. Methods: The current study included consecutive 98 radical prostatectomy specimens with 151 foci with different Gleason Grade (GG) patterns. Results: The highest frequency of PTEN loss was observed in GG4 cribriform and glomeruloid patterns (59.3%, p < 0.001). Combined score (CS) PD-L1 positivity was observed in fourteen patients (14.2%). Tumor cell (TC) and tumor-associated inflammatory cells (IC) PD-L1 positivity was observed in 10 (10.2%) and 7 (7.1%) patients. The highest frequency of PD-L1 expression was observed in the GG5 pattern, and between GG4 patterns, the irregular pattern had the highest PD-L1 positivity. Conclusions: In conclusion, in our cohort of consecutive unselected cases of prostatic carcinoma, we observed the highest PTEN loss rate in the GG4 cribriform and glomeruloid pattern and the highest PD-L1 expression rate in the GG5 and GG4 irregular patterns. These results may predict molecular differences between different histological patterns in PCa and may be used to inform a treatment decision. Future studies should investigate these differences between histological patterns of PCa to predict response to immunotherapy in larger cohorts.